Cell, tissue and organ culture can be used to produce biologicals, such as, proteins, nucleic acids and viruses. For example, the host cells of the culture naturally may express the product of interest, can be manipulated to express a product of interest, and perhaps at higher than normal levels, or can be transformed to carry and to express a foreign nucleic acid containing the genetic information encoding the product of interest The foreign nucleic acid or translation product thereof can be amplified in the host cells. The foreign nucleic acid can express not only a polypeptide but also a functional ribonucleic acid (RNA), such as an antisense molecule or a ribozyme, viral vectors, regulatory factors and so on.
Cell lines are another source of biological products and can serve as a means for amplifying introduced nucleic acids and obtaining expression products therefrom. The cells can be of random origin or can be obtained from a specific source in view of intended use and/or properties of the desired product.
Using cells and tissues to manufacture or to isolate a desired product may require implementing varying types of purification methods alone or in combination to obtain the product of interest. The range of purification methods implemented depends on, for example, the actual amount of desired product, the desired level of purity, the structural or functional similarity of the desired product to endogenous molecules of the host cell and so on. Thus, purification can entail mere lysis of the host cell or can include subsequent steps including immunoaffinity chromatography, size exclusion chromatography, electrophoretic separation, selective degradation by, for example, an enzyme, and gradient centrifugation.
Following the purification steps, it may be desirable to determine the amount of product present as well as the level of purity thereof. The level of purification can be determined in any of a variety of ways, for example, by determining the amount of specific protein as compared to total protein present in a sample. Alternatively, the amount of a specific contaminant of interest can be determined.